Generally, in a mobile communication system, handover needs to be established in a terminal in order to perform communication while securing mobility. The handover is not recognized by a user of the terminal but an operation which changes a base station is performed while maintaining call in a mobile communication system. Accordingly, the terminal performs control in accordance with the change of the base station to continuously maintain the call.
A lot of studies on for the handover technology have been conducted with respect to 2G/3G technology in a related art. Specifically, a study to prevent unnecessary frequent handover, such as a ping-pong phenomenon from occurring in a region where two cells overlap, has been conducted.
In order to solve the above-mentioned problem, a 3GPP Rel. 8 (LTE) system causes terminal history information (UE-history information) indicating information on a time when the terminal stays in each cell to be included in a field of a hand-over preparation information message to optimize the handover based on specific information of the terminal.
However, such a method does not uses information in an adjacent cell, specifically, a target cell so that there may be restriction to optimize the handover.
Therefore, the present invention has been made in an effort to provide an inter-region handover method in a communication system which includes a region monitoring step, a region rescanning step, a region redecision step, and a CoMP connection reconfiguration step in case where a terminal moves between regions in a communication environment in which a communication area, in which at least one base station provides a service, is divided into at least two of at least one center region, at least one boundary region, and at least one common region.
However, an object of the present invention is not limited to the above description and other objects which have not been mentioned above will be more apparent to those skilled in the art from reading of the following description.
An aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system including a step of monitoring a region where a terminal is located, in which the center region may be a region where only one base station provides a service, the boundary region may be a region where a base station set including at least two base stations provides a service, and the common region may be a region where a base station set, which includes at least two base stations including a base station which provides a service to at least one center region and at least one base station which provides a service to at least one boundary region, provides a service and the base station may be a communication node which manages resources for terminals located in a region where the base station provides a service.
In the monitoring step, the base station may monitor a region where a terminal, to which a service is provided, is located or the terminal may monitor a region where own terminal is located.
The monitoring step may comprise monitoring the region where the terminal is located, using channel quality indicators for at least one base station.
The monitoring step may comprise monitoring the region where the terminal is located using another channel quality indicator which is obtained by combining channel quality indicators for at least two base stations.
Further, the inter-region handover method may further include a step of rescanning a region where the terminal is located.
In the rescanning step, the base station may initiatively rescan the region or the terminal may autonomously rescan the region.
In the rescanning step, the terminal may rescan the region in accordance with a command of the base station.
In the rescanning step, the terminal may rescan regions which are configured by all or a part of base stations in a neighbor list which is provided by a base station or the terminal rescans regions which are configured by at least one base station which performs the CoMP transmission to the terminal in the neighbor list.
In the rescanning step, when the region shift is suspected as a result of monitoring a region where the terminal is located, by the terminal, the terminal may autonomously rescan the region.
Further, the inter-region handover method may further include a step of redeciding a region where the terminal is located.
In the redecision step, the base station may redecide a region of the terminal to which a service is provided and the terminal may redecide a region where own terminal is located.
The inter-region handover method may further include a step of reconfiguring CoMP connection between the terminal and at least one base station.
In the reconfiguration step, when the terminal moves to a region where the terminal needs to additionally establish the connection with at least one base station different from the at least one base station which is currently connected, after the region redecision, the connection with another at least one base station may be established to the terminal or when the terminal moves to a region where the terminal needs to release the connection with at least one base station among at least one base station which is currently connected to the terminal, after the region redecision, the terminal may maintain current connection configuration for a first predetermined time and then release the connection configuration with the at least one base station from which the connection configuration is released after the first predetermined time elapses.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, including performing region monitoring using another channel quality indicator which is obtained by combining channel quality indicators for at least two base stations.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system in which a terminal performs region rescanning of regions which are configured by at least one base station which performs CoMP transmission to a terminal in a neighbor list.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a terminal monitors a region where own terminal is located and when region shift is suspected through the region monitoring, the terminal transmits a region rescanning request message to a base station or autonomously performs the region rescanning.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a base station receives a CoMP scanning report (a channel quality indicator of at least one base station which is capable of performing the CoMP transmission to the terminal) from the terminal in a neighbor list.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a base station may transmit a CoMP establishment request message to another at least one base station and the base station may transmit a CoMP access connection reconfiguration message to the terminal after receiving a CoMP establishment response message from the another at least one base station.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a base station transmits a CoMP establishment request message to another at least one base station and the base station transmits the CoMP access connection reconfiguration message to the terminal after receiving the CoMP establishment response message from the another at least one base station and then transmits the CoMP establishment completed message to the another at least one base station after receiving the CoMP access connection reconfiguration completed message from the terminal.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a base station transmits a CoMP access connection reconfiguration message to the terminal and transmits a CoMP release request message to another at least one base station after receiving the CoMP access connection reconfiguration completed message from the terminal, and receives a CoMP release response message from another at least one base station.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a base station transmits a CoMP establishment request message to another at least one base station and the base station transmits the CoMP access connection reconfiguration message to the terminal after receiving the CoMP establishment response message from the another at least one base station and transmits the CoMP establishment completed message to the another at least one first base station after receiving the CoMP access connection reconfiguration completed message from the terminal, transmits a CoMP release request message to the at least one another second base station, and receives a CoMP release response message from the at least one another second base station.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which region redecision is performed during a CoMP connection reconfiguration step.
When the region redecision is performed during the CoMP connection reconfiguration step in the communication system, region redecision is performed during a CoMP connection reconfiguration step.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which if region shift of a terminal is decided, a base station performs region redecision for a first predetermined time.
If the region shift of the terminal is decided in the communication system, when the base station performs the region redecision for the first predetermined time, the base station receives a CoMP scanning report from the terminal for the first predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a terminal monitors a region where the terminal is located and when region shift is suspected through the region monitoring, the terminal autonomously performs the region rescanning and then performs region redecision.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, a base station receives a CoMP scanning report from the terminal for the first predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when a terminal moves to a region where the terminal needs to additionally establish the connection with at least one base station different from the at least one base station which is currently connected, after region redecision, at least one base station among at least one base station which is currently connected to the terminal transmits a CoMP establishment request message to another at least one base station, and when the terminal moves to a region where the terminal needs to release the connection with at least one base station among the at least one base station which is currently connected, after the region redecision, at least one base station which is currently connected to the terminal maintains the current connection configuration for the first predetermined time and at least one base station among the at least one base station which is currently connected to the terminal transmits a CoMP release request message to at least one base station which is supposed to release the connection after the first predetermined time elapses.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when a terminal moves to a region where the terminal needs to additionally establish the connection with at least one base station different from the at least one base station which is currently connected, after region redecision, the base station transmits a CoMP access connection reconfiguration message for establishment of CoMP connection to the terminal.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when a terminal moves to a region where the terminal needs to release the connection with at least one base station among the at least one base station which is currently connected, after region redecision, the current connection configuration is maintained for a first predetermined time and then a base station transmits a CoMP access connection reconfiguration message for the CoMP connection release, to the terminal after the first predetermined time elapses.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, if region redecision is performed during a first predetermined time and another region shift of the terminal is decided before the first predetermined time elapses, the region redecision is performed for a second predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, region monitoring is performed for a first predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, if region monitoring is performed during a first predetermined time and then region shift of the terminal is suspected before the first predetermined time elapses, region rescanning is performed.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, CoMP scanning and region redecision are performed for a first predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a terminal is controlled to continuously perform CoMP scanning and region redecision.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, a terminal may be controlled to perform CoMP scanning and region redecision for a first predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, if current connection configuration is maintained for a first predetermined time and then another region shift of the terminal is decided before the first predetermined time elapses, current connection configuration may be maintained again for a second predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, if CoMP connection reconfiguration is performed for a first predetermined time and connection configuration is maintained for the first predetermined time and then another region shift of the terminal is decided before the first predetermined time elapses, current connection configuration may be maintained for a second predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which when region shift of a terminal is decided, if current connection configuration is maintained for a first predetermined time and then another region shift of the terminal is decided before the first predetermined time elapses, CoMP connection reconfiguration is performed for a second predetermined time.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which a terminal performs region redecision and the terminal transmits a CoMP reestablishment request message including a region redecision result to a base station.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, in which region monitoring is performed during a CoMP connection reconfiguration step.
When the region monitoring is performed during the CoMP connection reconfiguration step in the communication system, region monitoring may be performed during a CoMP connection reconfiguration step.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, including a step of monitoring a region where a terminal is located and a step of rescanning a region where the terminal is located, in which the center region is a region where only one base station provides a service, the boundary region is a region where a base station set including at least two base stations provides a service, and the common region is a region where a base station set, which includes at least two base stations including a base station which provides a service to at least one center region and at least one base station which provides a service to at least one boundary region, provides a service and the base station is a communication node which manages resources for terminals located in a region where the base station provides a service.
Another aspect of the present invention provides an inter-region handover method for a communication area which is divided into at least two of at least one center region, at least one boundary region, and at least one common region in a communication system, including a step of monitoring a region where a terminal is located and a step of rescanning a region where the terminal is located, in which the center region is a region where only one base station allocates at least one resource to one terminal to perform communication, the boundary region is a region where a base station set including at least two base stations allocates at least one resource to one terminal to perform communication, and the common region is a region where a base station set, which includes at least two base stations including a base station which provides a service to at least one center region and at least one base station which provides a service to at least one boundary region, allocates at least one resource to one terminal to perform communication, the base station may be a communication node which manages resources for terminals located in a region where the base station provides a service.
Accordingly, the present invention suggests an inter-region handover method in a CoMP environment in which cooperative transmission between base stations is performed to provide mobility of a terminal.
According to an inter-region handover method according to the present invention, connectivity of a service of the terminal may be secured by suggesting a handover method in consideration of a characteristic for every region in accordance with a movement scenario of a terminal in a CoMP environment in which cooperative transmission between base stations is performed.
The inter-region handover method of the present invention performs connection reconfiguration after checking a continuous state of a region configuration condition for a predetermined time, thereby reducing signal overhead in frequent movement or ping-pong state of the terminal and reducing a load of a network.
In the inter-region handover method of the present invention, the terminal autonomously performs region monitoring so that the terminal can more exactly perform region monitoring using a channel quality which the terminal measures by itself.
In the inter-region handover method of the present invention, the terminal autonomously performs region rescanning, thereby reducing signaling between a base station and a terminal and shortening service delay.
In the inter-region handover method of the present invention, the terminal autonomously performs region redecision, so that the terminal can exactly perform region redecision using a region rescanning result which the terminal performs by itself and can quickly respond to frequent movement or ping-pong state of the terminal.